In existing display apparatuses, NOR gate circuit is frequently arranged as a logic gate circuit in a scan driving circuit for supplying scanning signal in a row direction. Currently, through different manufacture processes, many different types of elements can be employed to implement an NOR gate circuit in a scan driving circuit of a display apparatus, such as an a-Si (Amorphous Silicon) TFT (Thin Film Transistor), an LTPS (Low Temperature Poly-silicon) TFT or an Oxide type TFT, wherein an a-Si TFT has a mature manufacture process and a low cost but with defects such as a low mobility ratio and a poor stability, and an LTPS TFT has a fast speed and a good stability but with a poor uniformity, a high manufacture cost and an inadaptability of manufacture for those large-sized panels. Therefore, The technique adopting Oxide TFTs becomes more suitable for large-sized panel display in the future, due to its advantages such as a high mobility ratio, a good uniformity and a low manufacture cost.
However, a transfer characteristic of an Oxide TFT is usually of a depletion mode, meaning that TFT remains in a turning-on status in a case in which its gate-to-source voltage Vgs is equal to zero. Therefore, in a case in which an Oxide TFT is adopted to form an NOR gate circuit, a voltage at an output terminal will suffer a loss to some extent as a function of a magnitude of TFT threshold voltage, “threshold loss” for short, affecting operating performance of the NOR gate circuit.